[Assembler] Allow buffer id to be passed to MCAsmParser

[sanwou01]

Summary

The MCAsmParser assumes that the buffer it should parse is the one
containing the Main File. Generalize the AsmParser constructor to pass
in a buffer id.

[rengolin]

Hum, this sounds nasty. What kind of errors did you see? Could you devise a test?

[compnerd]

The inline assembly uses a local buffer (which is the "main" buffer). The SLoc is tracked for where the inline assembly was instantiated for provenance. This seems conflicting with the description. Furthermore, a test case is absolutely needed.

[sanwou01]

@compnerd, this is part of a larger set of patches that changes the inline asm SourceMgr to be used multiple times. It will land as part of D29441.

include/llvm/MC/MCParser/MCAsmParser.h

public:
   /// on error.
   /// \return - False on success.
   virtual bool parseParenExprOfDepth(unsigned ParenDepth, const MCExpr *&Res,
                                      SMLoc &EndLoc) = 0;
 };
 
 /// \brief Create an MCAsmParser instance.
 MCAsmParser *createMCAsmParser(SourceMgr &, MCContext &, MCStreamer &,
-                               const MCAsmInfo &);
+                               const MCAsmInfo &, unsigned CB = 0);
 
 } // End llvm namespace
 
 #endif

lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

void AsmPrinter::EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
 
   std::unique_ptr<MemoryBuffer> Buffer;
   if (isNullTerminated)
     Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
   else
     Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
 
   // Tell SrcMgr about this buffer, it takes ownership of the buffer.
-  SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
+  unsigned BufNum = SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
 
   std::unique_ptr<MCAsmParser> Parser(
-      createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI));
+      createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI, BufNum));
 
   // We create a new MCInstrInfo here since we might be at the module level
   // and not have a MachineFunction to initialize the TargetInstrInfo from and
   // we only need MCInstrInfo for asm parsing. We create one unconditionally
   // because it's not subtarget dependent.
   std::unique_ptr<MCInstrInfo> MII(TM.getTarget().createMCInstrInfo());
   std::unique_ptr<MCTargetAsmParser> TAP(TM.getTarget().createMCAsmParser(
       STI, *Parser, *MII, MCOptions));

lib/MC/MCParser/AsmParser.cpp

private:
   /// \brief is Darwin compatibility enabled?
   bool IsDarwin;
 
   /// \brief Are we parsing ms-style inline assembly?
   bool ParsingInlineAsm;
 
 public:
   AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
-            const MCAsmInfo &MAI);
+            const MCAsmInfo &MAI, unsigned CB);
   ~AsmParser() override;
 
   bool Run(bool NoInitialTextSection, bool NoFinalize = false) override;
 
   void addDirectiveHandler(StringRef Directive,
                            ExtensionDirectiveHandler Handler) override {
     ExtensionDirectiveMap[Directive] = Handler;
   }

 extern MCAsmParserExtension *createELFAsmParser();
 extern MCAsmParserExtension *createCOFFAsmParser();
 
 } // end namespace llvm
 
 enum { DEFAULT_ADDRSPACE = 0 };
 
 AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
-                     const MCAsmInfo &MAI)
+                     const MCAsmInfo &MAI, unsigned CB = 0)
     : Lexer(MAI), Ctx(Ctx), Out(Out), MAI(MAI), SrcMgr(SM),
-      PlatformParser(nullptr), CurBuffer(SM.getMainFileID()),
+      PlatformParser(nullptr), CurBuffer(CB ? CB : SM.getMainFileID()),
       MacrosEnabledFlag(true), CppHashInfo(), AssemblerDialect(~0U),
       IsDarwin(false), ParsingInlineAsm(false) {
   HadError = false;
   // Save the old handler.
   SavedDiagHandler = SrcMgr.getDiagHandler();
   SavedDiagContext = SrcMgr.getDiagContext();
   // Set our own handler which calls the saved handler.
   SrcMgr.setDiagHandler(DiagHandler, this);
bool parseAssignmentExpression(StringRef Name, bool allow_redef,
   return false;
 }
 
 } // end namespace MCParserUtils
 } // end namespace llvm
 
 /// \brief Create an MCAsmParser instance.
 MCAsmParser *llvm::createMCAsmParser(SourceMgr &SM, MCContext &C,
-                                     MCStreamer &Out, const MCAsmInfo &MAI) {
-  return new AsmParser(SM, C, Out, MAI);
+                                     MCStreamer &Out, const MCAsmInfo &MAI,
+                                     unsigned CB) {
+  return new AsmParser(SM, C, Out, MAI, CB);
 }